defconfigs: Migrate CONFIG_SYS_REDUNDAND_ENVIRONMENT

Move this symbol to Kconfig.  As part of this we can drop a UBI-specific
symbol that was a stop-gap for not having this particular symbol in
Kconfig.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/theadorable-x86-dfi-bt700_defconfig b/configs/theadorable-x86-dfi-bt700_defconfig
index d53aff0..e0678f4 100644
--- a/configs/theadorable-x86-dfi-bt700_defconfig
+++ b/configs/theadorable-x86-dfi-bt700_defconfig
@@ -42,6 +42,7 @@
 CONFIG_ISO_PARTITION=y
 CONFIG_EFI_PARTITION=y
 CONFIG_DEFAULT_DEVICE_TREE="theadorable-x86-dfi-bt700"
+CONFIG_SYS_REDUNDAND_ENVIRONMENT=y
 CONFIG_REGMAP=y
 CONFIG_SYSCON=y
 CONFIG_CPU=y